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Abstract: Flexible all-solid-state supercapacitors (SCs) are fabricated using graphene/carbon black nanoparticle (GCB) film electrodes and cross-linked poly(vinyl alcohol)–H2SO4 porous gel electrolytes (gPVAP–H2SO4). The GCB composite films, with carbon black (CB) nanoparticles uniformly distributed in the graphene nanosheets, greatly improve the active surface areas and ion transportation of pristine graphene film. The porous structure of as-prepared gPVAP–H2SO4 membrane improves the equilibrium swelling ratio in electrolyte and provides interconnected ion transport channels. The chemical crosslinking solves the fluidity problem of PVA–H2SO4 gel electrolyte at high temperature. As-fabricated GCB//gPVAP(20)–H2SO4//GCB flexible SC displays an increased specific capacitance (144.5 F g−1 at 0.5 A g−1) and a higher specific capacitance retention (67.9% from 0.2 to 4 A g−1). More importantly, the flexible SC possesses good electrochemical performance at high temperature (capacitance retention of 78.3% after 1000 cycles at 70 °C). [Copyright &y& Elsevier]

Abstract: Graphene single nanosheet (GNS) is synthesized from graphite by chemical oxidation and thermal exfoliation at 1000 °C and confirmed by X-ray diffraction analysis. Scanning electron and transmission electron microscope images clearly show the lateral expansion of graphite sheet and uniform dispersion of Pt nanoparticles on GNS. Fourier transform infrared and X-ray photoelectron spectroscopy analyses are conducted for surface properties of GNS such as oxygenated functional groups. Cyclic voltammetric analysis shows that electrochemical active surface areas (ECSAs) for Pt/GNS, commercial Pt/Vulcan XC-72 carbon black and Pt-incorporated onto commercial carbon black (Pt/CB) prepared in the laboratory are 33.1 m2 g−1, 23.5 m2 g−1 and 22.5 m2 g−1, respectively. Because of significant restacking of Pt/GNS sheets, carbon black (CB) with different content is intercalated between Pt/GNS as a spacer. The ECSAs of Pt/GNS, Pt/GNS/CB20, Pt/GNS/CB30 and Pt/GNS/CB40 are evaluated to be 31.5 m2 g−1, 28.6 m2 g−1, 38.8 m2 g−1 and 30.4 m2 g−1, respectively. The cell performance highly depends on CB content and Pt/GNS/CB with 30 wt.% of CB content shows the best cell performance of 400 mA cm−2. [Copyright &y& Elsevier]

Abstract: Antimony doped tin oxide supported on carbon black (ATO/C) has been synthesized using an in situ co-precipitation method, and platinum–ATO/C nanoparticles have been prepared using a consecutive polyol process to enhance the catalyst activity for the methanol oxidation reaction. The Pt–ATO/C electrocatalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microcopy (SEM), energy dispersive X-ray spectroscopy (EDS) and cyclic voltammetry. The Pt–ATO/C catalyst exhibits a relatively high activity for the methanol oxidation reaction compared to Pt–SnO2/C or commercial Pt/C catalyst. This activity can be attributed to the high electrical conductivities of the Sb-doped SnO2, which induces the electronic effects with Pt catalysts. Pt–ATO/C is a promising methanol oxidation catalyst with high activity for the reaction in direct methanol fuel cells. [Copyright &y& Elsevier]

Abstract: Highly dispersed Pt and SnO2 double nanoparticles containing different Pt/Sn ratios (denoted as Pt/SnO2/CB) were prepared on carbon black (CB) by the modified Bönnemann method. The average size of Pt and SnO2 nanoparticles was 3.1±0.5nm and 2.5±0.3nm, respectively, in Pt/SnO2(3:1)/CB, 3.0±0.5nm and 2.6±0.3nm, respectively, in Pt/SnO2(1:1)/CB, and 2.8±0.5nm and 2.5±0.3nm, respectively, in Pt/SnO2(1:3)/CB. The Pt/SnO2(3:1)/CB electrode showed the highest specific activity and lowest overpotential for ethanol oxidation reaction (EOR), and was superior to a Pt/CB electrode. Current density for EOR at 0.40 and 0.60V vs. reversible hydrogen electrode for the Pt/SnO2(3:1)/CB electrode decayed more slowly than that for the Pt/CB electrode because of a synergistic effect between Pt and SnO2 nanoparticles. The predominant reaction product was acetic acid, and its current efficiency was about 70%, while that for CO2 production was about 30%. [ABSTRACT FROM AUTHOR]

Abstract: Iron/carbon-black composite nanoparticles were synthesized by chemically reducing the iron salt mixing with carbon black by adding NaBH4 in the aqueous solution. Carbon-black particles, with a mean particle size of approximately 40nm, function as the nucleation cores for iron deposition. Additionally, core–shell iron composite particles are observed to be 30–100nm with spherical sharp. At the first time discharge, the iron/carbon-black composite nanoparticle discharged 1200mAhg−1(Fe) at plateau one and 400mAhg−1at plateau two at a high current density of 200mAg−1(Fe). The capacity is larger than the theoretical value, which is attributed to the formation of iron hydride (FeH x ) while the iron was reduced by NaBH4, followed the hydrogen reaction as an active material while the battery discharge occurs. In further cycles, the iron/carbon-black composite iron electrode shows a good reversibility of about 600mAhg−1(Fe) when the nickel–iron battery operated between 1.65 and 0.8V. XRD analysis results indicate that the carbon black in the core of the iron/carbon-black composite enhances the reduction/oxidation reactions of iron, as achieved by the carbon black forming an enhanced electronic conductive network while iron is discharged as the insulator species such as Fe(OH)2 and Fe3O4. SEM images reveal that the iron/carbon-black composite keeps particle sizes smaller than 300nm during the electrode cycling, indicating that carbon black also acts as the nucleation cores for the dissolution–deposition of iron. [Copyright &y& Elsevier]

Maximizing the rate capability of carbon materials optimizes sodium ion battery (SIB) performance. This study develops nanoscale nitrogen-doped carbon material (NNCM), in which nano-sized primary particles aggregate. These aggregates form a meso–macro-hierarchical porous structure, which facilitates Na+ diffusion from outside the aggregates into the primary nanoparticles. The large specific surface area of carbon black improves Na+ accessibility by forming large interfaces, and Na+ is easily solvated through defect sites and pores on the primary particle surfaces. Furthermore, primary nanoparticles have short Na+ diffusion pathways, while turbostratic structures provide broad pathways aiding Na+ diffusion. Nitrogen improves the electrical conductivity of the carbon matrix and provides abundant active sites by creating extrinsic defects. Together, these factors afford NNCM good capacity retention (38% at 100 A/g vs. 1 A/g), reversible capacity (~101 mAh/g at 100 A/g), ultrahigh cycling stability (11,000 cycles at 100 A/g), high initial coulombic efficiency (80%), and remarkable rate capability. • A solution plasma process doped nitrogen into hierarchical porous carbon materials. • Carbon materials facilitated co-intercallation of Na+-DEGDME. • Nitrogen doping increased conductivity and active sites for Na+ adsorption. • Cells showed high rate capability , retaining 38% of capacity at 100 A/g vs. 1 A/g. [ABSTRACT FROM AUTHOR]